Content Adaptive Backlight Control (CABC) is a method for analyzing contents of displaying and adjusting backlight of display panel based on contents of gray level and Gamma correction technology.
In present panel display control system, all of the modulation functions of CABC transmit Pulse Width Modulation (PWM) waves from display driving chip to PWM pin of backlight driving chip in order to implement brightness modulation of backlight, and then modulate brightness of a liquid crystal display device.
When video frame data enable signal of liquid crystal display panel during a frame data disable period, brightness of the liquid crystal display device should be constant because PWM wave doesn't change. However, video frame data on liquid crystal pixels are not updated state, meaning that liquid crystal pixels is in charge sustained state, but leakage characteristic of thin film transistor itself causes the decline of pixel voltage of liquid crystal pixels to reduce brightness of the liquid crystal display device.